Paraphyletic groups are not clades and are therefore likely to be superseded systematic taxonomy, though they may be used for convenience for some time, especially if they correspond to an intuitively appealing group. An example is the lay concept of fish, one definition of which includes mammals, such as whales, as well as sharks, sturgeon, and scaled fish, the common ancestor of which is some ancestral vertebrate, from which amphibians and reptiles are also descended.